High inter-observer reliability in standardized ultrasound measurements of subcutaneous adipose tissue in children aged three to six years

Figures

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  Fig. 1. Brightness-mode ultrasound imaging of SAT. a Example of an ultrasound image taken at the site distal triceps. Within the region of interest, the software evaluation algorithm automatically measured subcutaneous adipose tissue thickness (SAT) along 118 vertical lines from the lower border of the dermis to the upper border of the muscle fascia. Mean SAT thickness (d) including embedded fibrous structures (dI) was 8.1 mm, excluding embedded structures (dE), SAT thickness was 7.5 mm. b Ultrasound measurement sites: upper abdomen (UA), lower abdomen (LA), erector spinae (ES), distal triceps (DT), brachioradialis (BR), lateral thigh (LT), front thigh (FT), medial calf (MC). c Series of evaluated ultrasound images: image depth was 30 mm, sum of SAT thicknesses at the eight sites including embedded structures (DI) was 36.1 mm (DE = 33.0 mm). Thicknesses of individual sites dI (dE in parentheses) at UA: 2.1 mm (1.6 mm), LA: 3.8 mm (3.4 mm), ES: 2.9 mm (2.9 mm), DT: 7.2 mm (6.4 mm), BR: 4.4 mm (4.2 mm), LT: 6.3 mm (5.5 mm), FT: 5.9 mm (5.5 mm), MC 3.5 mm (3.5 mm)

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  Fig. 2. SAT thickness sums from eight sites measured three times in each of the 20 participants. a SAT thickness sums including embedded fibrous structures (DI) plotted against the mean value of the three observers. Pearson’s correlation coefficient r = 0.997, standard error of the estimate (SEE) = 1.1 mm, and intra-class correlation coefficient (ICC) = 0.998 (95% CI: 0.980–0.999). b SAT thickness sums excluding embedded fibrous structures (DE). r = 0.998; SEE = 1.02; ICC = 0.998 (95% CI = 0.995–0.999)

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  Fig. 3. Observer differences from the mean. Individual observer differences (Δ) from the mean of the three measurements (DMEAN) are shown for each participant (see Table 2). a Individual observer differences from DMEAN including embedded structures (DI,MEAN) calculated as ΔI = DI–DI,MEAN are shown. Standard deviation (SD) of observer differences was 1.1 mm, 95% of the measurements were between ±2.1 mm (limits of agreement). b Individual observer differences ΔE = DI– DE,MEAN are shown. SD of observer differences was 1.0 mm, 95% of measurements were between ±2.0 mm (limits of agreement)

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  Fig. 4. Absolute measurement differences at the individual sites. Absolute differences ABS(δ) of each observer from the mean of the three observers were compared at each site (n = 3·20 = 60). a ABS (δI) for each of the eight sites including embedded fibrous structures. b ABS (δE) for each site excluding embedded fibrous structures. Upper abdomen (UA); lower abdomen (LA); erector spinae (ES); distal triceps (DT); brachioradialis (BR); lateral thigh (LT); front thigh (FT); medial calf (MC). Outliers are shown as circles, extreme values as stars